Pope Benedict XVI waves to the crowd from a balcony at Castel Gandolfo, Italy. The pontiff became the first pope in 600 years to retire as leader of the Catholic Church. Vincenzo Pinto, AFP/Getty Images

People cheer as Pope Benedict XVI greets the crowd from a balcony at Castel Gandolfo. Luca Bruno, AP

A helicopter carrying Pope Benedict XVI leaves the Vatican.The pontiff flew to Castel Gandolfo, Italy, where he will become the first pope in 600 years to retire as leader of the Catholic Church. Michael Sohn, AP

People watch from an observation platform on St. Peter's Basilica. Peter Macdiarmid, Getty Images